Flutterのボタン有効/無効切り替えのサンプルアプリケーション
$ flutter --version
Flutter 3.3.1 • channel stable • https://github.com/flutter/flutter.git
Framework • revision 4f9d92fbbd (6 months ago) • 2022-09-06 17:54:53 -0700
Engine • revision 3efdf03e73
Tools • Dart 2.18.0 • DevTools 2.15.0